While orbiting over the Indian Ocean a year ago, astronauts aboard the International Space Station saw an atmospheric halo skirting the edge of the Moon.

At the time, the Moon was in its waxing crescent phase. It would have appeared to the naked eye as just a very thin crescent, showing here as the brightest part to the bottom right, but the astronaut’s camera captured enough light from the rest of it to make it appear more like a full Moon.

The halo effect appears to the bottom right of the Moon. This was likely the result of sunlight refracting as it passed through tiny ice crystals very high in the Earth’s atmosphere – up in the mesosphere, within the broad blue band of the upper atmosphere showing here. Unlike all the named halo phenomena we see as sunlight shines through ice crystals in the low atmosphere, extreme-altitude halos like this don’t tend to have names because no one gets to see them.

The lower, whiter atmospheric band is the stratosphere. The deep orange one below that is the troposphere, the one nearest to the Earth’s surface (appearing completely black here). That lowest layer of the atmosphere is where our weather is and where all human life happens – all apart from that of a handful of halo-spotting astronauts way up above.